


A Lesson

by RaonOfDemons



Series: Kai's Growing Up [1]
Category: Avatar: Legend of Korra, Avatar: The Last Airbender
Genre: Blow Jobs, First Time Blow Jobs, Hand Jobs, M/M, Masturbation, Puberty, Smut
Language: English
Status: Completed
Published: 2020-04-21
Updated: 2020-04-21
Packaged: 2021-03-02 01:40:40
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,934
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23767066
Author URL: https://archiveofourown.org/users/RaonOfDemons/pseuds/RaonOfDemons
Summary: Kai is getting older now. As he is getting older is body is beginning to change and react. During an air bending lesson Kai experiences something and gets scared and so when Mako is there he asks him for help. Set sometime between Books 3 and 4
Relationships: Kai/Mako, Kai/Mako (Avatar), Mako/Kai, Mako/Kai (Avatar)
Series: Kai's Growing Up [1]
Series URL: https://archiveofourown.org/series/1713418
Kudos: 22





	A Lesson

**Author's Note:**

> Hello everyone! This is my FIRST every smut (is smut the right word?) fan fiction! I have never written one of these before so I hope you like it! Why Mako and Kai you ask? Cause Mako and Book 4 Kai are hot. Any who, enjoy the story and be sure to let me know what you think!

It was a nice day at the Northern Air temple. Since it was everyone's day off all of the new air benders were off relaxing, Tenzin was spending time with his family, and Asami, Bolin, and Mako, who were visiting from Republic City, were on their own as they toured the temple. Where was Kai though? Well, he was in a secluded part of the temple all alone, thinking about stuff. He was getting older now and his body was beginning to change. He noticed he began to grow more hair, his muscles became more defined, his voice got deeper, and his little friend below was not so little anymore. Kai thought nothing of it at first really. He just carried on with his life as he assumed it was the same thing as getting taller, until one day that was…

2 weeks ago…

It was another long and boring airbending lesson from Tenzin. Everyone was in rows, with Kai being in the back. It was a hotter than usual day here at the Northern Airtemple and so people were wearing as little clothes as possible. The ladies wore comfortable tank tops and shorts and the gentlemen wore shorts and tank tops, except a couple, one of them being Tenzin. Kai was listening and following directions for a bit until his mind and eyes began to wonder. Kai gazed down Tenzin's body. He never really paid much attention, but now he began to notice something. Tenzin was a lot more muscular than he thought as this was the first time he never really had his robe on. Kai admired his chest and abs for a while, but soon his gaze went further down towards Tenzin’s dick, but only for a split second. 

He quickly snapped back to reality when he felt some tightening down in his shorts. Kai looked down to see something he never had before. His dick was getting hard and it scared him. Thankfully he was in the back row so no one could see. Kai began to worry. He had no idea what was happening and how to stop it. Kai had to get out of there now before someone noticed or else he would be really embarrassed. Kai picked up his tank top that was on the ground and covered himself with it so no one could see his hard on.

“Uh, hey Tenzin! I’m going to head to the restroom!” Kai said as he ran off.

Tenzin rolled his eyes and yelled back, “Alright, but be quick!”

Kai ran to the bathroom he knew no one would go into and locked the door. He rushed over to the toilet and pulled down his pants to reveal what was inside… His normal 4-inch soft dick was now a full on 6-inch hard on. Kai freaked out even more, thinking it was infected or something! After worrying a bit more he took a deep breath and reached down and grabbed it.

A small moan escaped Kai’s mouth. His touch on his dick felt oddly good and he did it some more. He was running his finger along it, up and down. He then ran it all the way down to his tip and a bigger moan came out this time. He didn’t understand much, but he liked it and so he kept rubbing the tip of his dick more and more until he had this feeling, as if he was about to pee. He quickly stopped and got scared as his heart was racing. He relaxed a bit more and went to do it again until a knock at the door made him jump.

“KAI! You are to report back to the lesson immediately!” “Yelled Meelo from the other side.

Kai jumped and panicked. “I’ll be out in a minute!”

“I was told to bring you back so I am not leaving until you come out!”

Kai sighed and looked back down at his dick to see it had softened now. He questioned it, but was rudely interrupted by Meelo banging on the door again. And so Kai pulled up his pants, put on his tank top and returned back to the lesson with Meelo.

Present…

Kai wondered about that day and why his dick got hard. He even questioned why it felt so good, but then why it felt like he was about to pee. He had looked in the library one day for a possible book explaining his issue, but to no luck he found nothing and so he went some days alone in his room just dealing with a hard dick, scared of what would happen from that “pee feeling”.

Kai wondered who he could talk to about this. Tenzin? No! He was afraid of what he would do or say. He might try some weird Air nomad doctor treatment. Bumi? Nope, trying to explain it to him would be useless. Bumi would get distracted 2 seconds into the conversation. Bolin? Kai thought about this for a moment, but thought Bolin might overreact about it and tell people.

When Kai couldn’t think of anyone else he sighed and looked out his window and saw Mako walking by and then.. DING! Mako. Kai could ask Mako. Kai knew that if something was wrong Mako would keep it a secret and help him out. Kai rushed out of his room and outside to where he saw Mako and ran up to him.

“Oh, hey Kai. What’s up?” Mako said stretching in his classic outfit, showing off his toned arms.

“Hey, um… I… Well…” Kai had no idea how to bring this issue up to Mako.

“Yeah…?”

“It’s just that…”

“What is it kid? I don’t have all day.”

Kai looked around and decided it would be better to talk to him in a more private area, his room. “You know, I need to talk to you in private. Could we head to my room?”

“Why? What did you do now? Is Tenzin going to kill you?”

“No! Just, please?”

“Fine.” Mako huffed.

Mako followed Kai as he led him to his bedroom. Kai seemed to be in a bit of a hurry, noticed Mako, as he sped walked and avoided the two people they walked by. It did not take long to arrive at Kai's bedroom since he was walking fast. Kai let Mako enter first, following behind him as he closed the door, and locked it, which Mako did not know. Mako stood in the middle of the room and Kai walked over and sat on his bed, looking down.

“Alright kid, what is it? You dragged me all the way here so it better not be something stupid.”

Kai took a couple deep breaths before he began to talk. “Okay… As of recently there have been some changes…”

“Okay?”

“With these changes, came something and I don’t know what to do about it. It’s just that… sometimes my penis gets hard and swol-” Kai didn’t have to even finish for Mako to know where this was going. His cheeks became red as he was so uncomfortable for this to be happening. “Len. I don’t understand what is happening at all and you seem like the only person here I can trust to take me to a doctor about this!”

A doctor? Did he just say he needs to see a doctor about this? Mako had to keep in a little laugh. He knew that what Kai meant was that he was getting a boner and from the sounds of it, Kai had no idea what they were, which surprised Mako. He thought the former runaway-thief kid would have picked up on some of that knowledge with how noisey he is. Mako just stood in there in silence for a bit.

“Well, can you help me?”

“I’m sorry… I mean, couldn’t have you talked to Tenzin about this?” The last thing Mako wanted to do was explain the whole puberty thing to Kai.

“No! He is the last person I want to go to! I don’t know what kind of weird air nomad stuff he will try to do!”

Mako had to hold in another laugh. “Alright… listen Kai,” He really didn’t want to do this, but he could tell Kai trusted him and Mako knew himself that all the other guys here wouldn't be much help and so Mako had to play the “big brother” role again like he did for Bolin when they were younger. “You don’t need to see a doctor about that.”

“R-Really?!”

“Yes. You are perfectly fine.”

“What do you mean? It has been happening more and more lately and I don’t know how to stop it!”

Oh dear, Mako thought to himself. He pulled up a chair and sat across from Kai who was on the bed, “What you are experiencing Kai is perfectly normal. What you are getting is called a boner.”

“A boner?”

“Yes, a boner. It’s what happens when you dick gets hard from…” He really hated this, but he knew he had to help Kain understand, “excitement… especially… sexual excitement.”. Mako turned his head away a bit as his cheeks reddened again.

“Huh… okay…” Kai took this knowledge and understood it somewhat. “But, how do I stop it? I don’t want anyone seeing me with a boner!”

“Well, around your age and until you mature and get older you’ll get a boner even when you don’t want one to happen. It’s kind of something you don’t have much control over. Later on you will only start to get them when you are in a sexual situation.”

“B-But… That’s another 6 years for me! How am I supposed to deal with this?!”

“There is one way…”

“Really? What?!”

“It’s called masturbating, but most guys say jerking off.”

“That’s weird? What does ‘jerking off’ do exactly?”

“Oh! Um, yeah… It’s… well, it is when you grab your dick and stroke it until… release.”

“I see… I tried to do that once but th-” Kai stopped speaking.

“Hey? You alright?” Mako asked. He looked into Kai’s eyes and knew. Mako drifted his eyes downwards to see a tent growing in Kai’s shorts.

“I’m kind of uh…”

“I can see that…” Mako coughed, choking on some air. He hasn’t felt this uncomfortable in awhile.

“I guess I could do that ‘jerking off’ thing you said…” And with no hesitation Kai stood up and pulled down his pants, now being completely naked to reveal his full 6-inch length, very close to Makos face.

“What the hell kid?!” Mako turned away in a flash.

“What?! I thought you were gonna teach me!”

‘What gave him that idea!?’ thought Mako. He heard Kai sit back on the bed and sigh. Mako felt bad for making Kai feel embarrassed. His older, caring, brother instincts kicked in and he turned around slowly to be greeted by Kai and his boner sticking straight up. When he turned slowly he really took in Kai for once and noticed how toned he looked… his jawline… his chest… his almost-abs… his di- NO! What was he thinking?! Mako closed his eyes and took a deep breath before opening them again.

“So…” Kai said.

“Yeah… I’ll teach you what I can…”

“Awesome! You really are the best Mako! So, what do I do first?”

“Um, well first you grab your hand around your sick.”

“Around it?”

“Yeah… around it…”

“Could you show by doing it too?”

“WHAT?!”

“What?! I mean, since you have a boner I thought you could do it too and I could copy what you do.”

Mako looked down and saw the tent in his pants. That noisy kid had seen Makos boner, but why did he have one?! I mean yeah he hadn’t had sex since he and Asami broke up over a year ago, but there was no way Kai was giving him one. “I-I Don’t think that is a good idea Kai…” He said nervously laughing.

“Oh come on! I want to make sure I am doing this right so if it ever happens again I will know what to do. And besides, you are the person I trust the most with… well… this.”

Mako couldn’t believe this was happening. Was he actually going to jerk off in front of Kai to show him how it is done? I mean, he could deny it and just make Kai do it alone, but there was something about Kai and what he said that he felt guilty and like he had to do it. “I… alright fine! But do not tell anyone about this or I will scorch you alive!”

“Hey, I won't tell anyone if you won't tell anyone that I asked you about this.”

Mako sighed in agreement and stood up. He couldn’t believe he was about to do this. He took off his jacket, leaving him in his white tank top and pants. Mako was hesitant at first, but slowly he grabbed onto his pants and slowly began to pull them down until POP!

“Wow…” was all Kai said to make Mako blush and his dick twitch a little.

Right in front of Kai's face was Mako's full 8-inch dick in its full glory. Mako didn’t know what to do at this point and so he stood there awkwardly, scratching the back of his head and his pants at his ankles.

“So, are you gonna show me how to do this?”

“Oh, right!.” Mako sat down in his chair. There he and Kai sat across from each other getting a full view of one anothers hard ones. “So first you can do this.” Mako said as grabbed his dick

“Alright.” Kai followed him and grabbed his own dick.

“And the rest is simple pretty much. You just move it up and down until, well you’ll know when you get there.” And Mako began to slowly move his hand up down on his hard dick. Kai continued to follow Mako’s simple instructions, but somehow seemed to not be doing it so well. “No kid, like this.” Mako tried showing Kai again. Mako just moved his hand up and down on his dick, but Kai still struggled like a dumbass.

“Ugh, I can’t… You think you could try for me?”

“T-Try?! F-For you?!

“Yeah… Do what you are doing on me? I’m not doing it right!

“Kai… listen I don’t know. That’s not right! I think that is too far for me.”

“Mako please! You are the only one helping me out with this! I can’t spend forever struggling when I get these… boners!”

Mako did not know what was going on, but he strangely wanted to help Kai and touch his dick. Mako’s mouth watered looking at it and his dick twitched against his will.

“Okay… Okay fine. I’ll do it… lean back.” Mako said as he scooted the chair closer. He could not believe he was about to do this. Kai leaned back, using his arms to prop him up. He watched closely as Mako brought his hand to his dick and grabbed it.

“Mmm…” Kai couldn’t help, but a moan escaped his mouth, which sent a shiver right down to Mako’s dick. Kai had never had anyone else touch him there and it felt really good.

“I’m gonna start now… if that’s okay.” Mako had no idea why he said that, just anything to make the quiet less awkward.

“Yeah… go ahead.” And so slowly Mako began to move his hand up and down, stroking Kai’s dick.

“Oh wow, that feels... nice.”

“Just wait until you get a blow job, heh…” WHAT?! MAKO WHAT DID YOU JUST SAY?! Mako was getting so horny jacking off Kai that he could not believe he let that one slip! Although, he could really use a blow job right now…

“What’s a blow job?”

“Eh… don’t worry about it right now. Just watch and learn what I am doing.” 

Kai nodded and went back to watching. Mako stroking his dick felt so good and even more good as time passed. Kai’s head rolled back in pleasure, a new feeling of pleasure he never experienced before. His breathing began to pick up and pace. Mako noticed this and began to stroke Kai a little faster. He kept going and going and-

“Wait stop! I think I’m gonna pee!” But Mako did not stop.

“You aren’t! Trust me! Just let it happen!”

Kai fidgeted a bit, but began to relax again and his breathing picked up more and more. Mako knew he was close and so he began to stroke Kai faster again, occasionally running his thumb over the tip of Kai’s dick and using his other hand to rub Kai’s balls.

“Oh shit… Mako… It’s happening!”

And with one final quick wave of stroking Kai erupted all over his chest. He came for what seemed like forever and finally began to settle down. Mako took his hand off of Kai’s dick and leaned back in his chair, taking in what he thought was one of the biggest loads he had ever seen.

“That felt… amazing!”

“Yeah… you think you know how to do it on your own now?”

“Yeah, I do. Thanks Mako.” Kai said sitting up. They sat in silence for a moment and then Kai finally spoke up “So, just curious… but what was that thing you mentioned earlier? A blow job?”

“Oh!” Mako was shocked. He had forgotten he said that and wished Kai had too, at least he did for a second… “It’s uh, nothing!”

“Mako… come on! You can’t leave me hanging! You gotta tell me!”

Mako, who was extremely horny after what he just witnessed as willing at this point to get a blow job from Kai and so he thought ‘screw it’ and would tell him.

“Well… It is when someone sucks your dick.”

“Suck? Like put it in your mouth and suck?”

“Yeah…”

“Sounds… weird.”

“It might at first, but it feels sooo good!” Mako said as he leaned back in the chair, stretching a bit causing his still hard on to stick straight up.

“I see…” Kai said, eyeing Mako’s dick. He thought to himself for a moment before coming to a conclusion. “I can give you a blow job.”

“What? No no no no!” But also kind of yes…

“Yeah… I mean, you just did something for me so I feel as if I should return the favor.”

“I mean… if you really want to… go ahead.” Mako’s heart was racing.

“Okay…” Kai got off the bed and knelt down in front of Mako’s dick.

“Just be careful, alright? Don’t scratch my dick with your teeth. Just suck on it. In and out.

Kai nodded. He grabbed onto Mako’s dick for the first time, which felt really heavy to him, and Mako let out a tiny gasp. Kai looked up at Mako, but Mako gave him a nod to continue. Slowly, Kai opened his mouth and took the tip of Mako’s dick in.

“Fuuuuuuccckk!”

“What?! Did I do something wrong?!” Kai said, taking the tip out.

“No! You were doing great. Don’t stop. Just keep going. I’ll tell you to stop if I need you to.”

Kai nodded again and slowly took the tip back into his mouth, sucking on it for a second, causing Mako to let out another moan. Kai slowly began to take more into his mouth, but horny Mako was almost gonna lose it so he decided to help Kai a bit.

“Here kid, like this.” He took his hand, placed it onto Kai’s head and shoved him down so he took it all into his mouth. This caused Mako to lean his head back and moan even more. “Mmmmm... fuck!”

Kai gagged a little, but managed to adjust quite quickly. Mako guided Kai by moving his head with his hand. Up and down Kai went on Mako’s dick. For someone who was inexperienced, Kai felt really good on his dick. 

Mako looked down to watch Kai sucking his dick. Just watching him between his legs turned him on even more. Mako went to rub his face, but before he did he noticed he had some cum on his hand from when he was jerking off Kai. Boy oh boy did that really get Mako going. Make tried his own cum once and it was alright, but he was curious about Kai’s and so he brought it to his mouth, looked at Kai first to make sure he wasn’t looking, and then stuck his cum covered hand into his mouth. Fuck. Kai tasted so good. So Good that it got Mako going and brought him close to his climax. Mako didn’t want Kai to swallow his load. Even though he was hella horny he was still thinking straight, a little. Kai was still new to this and so he shouldn’t have to do that… yet.

As Kai sucked a little bit more Mako pulled him off, grabbed his dick, and began to jerk off his dick that was covered with Kai’s saliva. He stroked with all of his might, and then...

“Did I do somet-” Kai was cut off as Mako let out a loud grunt and moan as he exploded all over himself, cum landing on his chest and abs, and some landing on Kai’s face!

“Ohh fuck!” Mako continued to stroke himself as he shot 4 more ropes of cum all over himself before finally settling down in his chair. “Wow Kai… that was amazing.”

“Really? I did it alright?”

“Kid, that was more than alright.” Mako said, wiping his forehead.

Kai smiled and stood. While Kai walked over to pick up a towel to clean himself up Mako brought his hand to his mouth eating his cum off his hands. He stopped though when he looked over and saw Kai bending down revealing his ass and tight hole. ‘Fuck’ Mako thought to himself. He might have to come see Kai again for another lesson. He was cut off from his thoughts when a towel was thrown at him.

“There, so you can get cleaned off.” Kai said as he was wiping himself down “Ugh, I’m gonna have to shower again… Did you have to get that stuff all over me? It’s gross and sticky!”

“Kid, for starters that stuff is cum, and it is not gross. Trust me.” Mako said cleaning himself off and getting dressed again.

“Hm, if you say so.”

“I do… Listen, there is still more to learn about this boner stuff and puberty. Would you want me to come back tomorrow night maybe? And teach you some more?”

“Oh… I would love that! Thank you Mako!” Kai said as he put on his shirt.

“No problem… Oh and don’t tell anyone about this… EVER!” Mako said, giving his classic glare to Kai before walking out of the room. Kai let out a little laugh before picking up the towel Mako left and bringing it over to his dirty clothes basket. He couldn’t help but bring it up to his nose and take a whiff before putting it away.

Mako walked outside and sat on a bench. He had to process what just happened. He never thought he would do that, especially with Kai, but he was so horny at that moment and there was something about Kai that turned him on, he didn’t know what came over him. He should be feeling guilty right now, but he doesn’t all he is thinking about Kai’s beautiful body and what he is gonna do in the next lesson with Kai…

**Author's Note:**

> Thanks for reading everyone! Let me know any thoughts or feedback you had please! Now, am I going to write a chapter two? Well, only time will tell...


End file.
